In recent years, in video display devices such as television receivers, liquid crystal displays, and plasma displays, it has been common not only to faithfully reproduce video images, but also to improve sharpness by edge enhancement, in conjunction with improvement in image quality of video signals.
In addition, start of digital broadcasts and spread of multiple channel broadcasts have allowed for commercialization of many kinds of video display devices having multiple-screen display capability.
On the other hand, in contour correction technologies using edge enhancement, a contour correction component which is affected by a signal of a period other than a video effective period at a boundary between the video effective period and the period other than the video effective period is extracted, causing unnatural overcorrection in a boundary portion. Moreover, when a plurality of screens are displayed, a contour correction component in association with signals with no correlation of both screens A and B is extracted in a boundary portion between screens A and B, causing unnatural contour correction as well. In order to prevent such overcorrection in a peripheral portion of a screen and unnatural contour correction in a boundary portion between a plurality of screens, for example, video display devices which deactivate contour correction in peripheral portions of a screen and in boundary portions between a plurality of screens are proposed in Patent Document 1.
Patent Document 1: Japanese Unexamined Patent Application Publication No. H11-088725